Ricciardo has been confirmed as Sebastian Vettel's new team-mate at Red Bull in 2014, replacing the outgoing Mark Webber. Vettel himself graduated from Toro Rosso at the end of 2008 but Horner said it is unfair to try and compare the two at this stage as the competitiveness of the junior team had changed in that time.

"Daniel's points have been limited because of the machinery that he's been sitting in," Horner said. "It's difficult to compare different times because [in 2008] Toro Rosso obviously had a car that was virtually identical to the chassis that we had. Sebastian's talent was obvious, we signed him in Hockenheim that year and of course he went on to win the race here in the wet in Monza later that year. There's rain forecast on Sunday; who knows?!

"But what you have to look at is the equipment available to Daniel is different, so therefore you're trying to judge a driver in the equipment at his disposal. I think we're fortunate that Toro Rosso has two very strong drivers in Jean-Eric Vergne and Daniel and it's that investment in youth that Red Bull has committed to over the years that has provided this opportunity on merit to Daniel, because we've always said we want the best two drivers and there was never a prerequisite that it has to be a Red Bull junior driver - only if they're good enough."

Horner also insisted that no decision had been made until after the Belgian Grand Prix and that the full Red Bull hierarchy of himself, Adrian Newey, Dietrich Mateschitz and Helmut Marko were in agreement.

"Spa was exactly as I said - there was nothing confirmed at that point - and I think even during the Spa weekend options were still very much open to us. So we took a bit of time after Spa to sit down - Adrian and myself - to discuss the scenarios and then obviously with Dietrich and Helmut, and we all reached the conclusion that Daniel was the best candidate for the medium and the longer term.

"Based on the test he did for us at Silverstone, based on what we'd seen how he's performed in a Toro Rosso, how he's performed on the simulator, having watched him develop and evolve as a driver over the last few years we decided to give him the chance and for him to replace Mark. So it was really in the aftermath of Spa that we came to that conclusion."